Power-driven wheels for civilian vehicles—as described, for example, in U.S. Patent Application Publication US-A-2005/0035676—are known which comprise a hub supporting a tire, and an axial-flow electric motor connected functionally to the hub.
More specifically, the axial-flow motor comprises an annular stator having coils, through each of which an alternating current flows; and an annular rotor connected magnetically to the stator, and having an output shaft connected mechanically, either directly or via a reducer, to the wheel hub.
The rotor has a number of permanent magnets arranged with alternate polarities facing the stator coils.
The permanent magnets generate magnetic flux directed predominantly along an axis of the rotor, and in turn generating an electromagnetic torque on the coils in known manner. The coils being angularly fixed, and therefore prevented from rotating, rotation torque is generated by reaction on the rotor, and rotation of the rotor rotates the output shaft, thus making power available to the wheel hub.
Publication US-A-2005/0035676 does not clearly specify the relative position or connection of the electric motor rotor and wheel hub.
Military vehicles require power-driven wheels capable of generating more or less the same power as axial-flow electric motors, and which at the same time are axially compact.
More specifically, the power-driven wheels must be capable of generating considerable power to overcome steep slopes and/or travel over muddy and/or marshy terrain.
Military vehicle certification tests also require that vehicles be capable of extremely steep hill starts, e.g. of 60%.
The power-driven wheels must also be axially compact, to make the best use of available space on military vehicles, and, for safety reasons, to expose as few operating component parts as possible.
Military vehicles also require fast, easy replacement of the axial-flow electric motor.
Military vehicles also require wheels equipped with cooling assemblies that can be changed without working on the wheel hub.
Finally, military vehicles also require fast tire inflation, without dismantling the hub-electric motor assembly.